An optical lens generally has an aperture stop, or even is equipped with an aperture-adjustable stop, that is, the size of aperture of the optical lens can be automatically or manually adjusted. In a conventional optical lens, the aperture-adjustable stop is disposed within the lens system or between any two lenses. This type of optical lens has to provide enough space for accommodating the structural components or electric control components used to mount the aperture-adjustable stop, and therefore there exists a problem of this type of optical lens which is unable to be further thinned.